1. Field of the Invention
The present invention relates to a method for manufacturing an ink jet recording head, an ink jet recording head, and an ink jet recording method.
2. Related Background Art
Among ink discharging methods of ink jet recording systems which have widely been used, there are a method in which electrical/thermal converting elements (heaters) are used as discharge energy generating means used for discharging ink droplets and a method in which piezo-electric elements are used. In these methods, discharging of the ink droplet can be controlled by an electrical signal. For example, the ink droplet discharging method utilizing the electrical/thermal converting element is based on the principle according to which ink near the electrical/thermal converting element is instantaneously boiled by applying the electrical signal to the electrical/thermal converting element and abrupt growth of a bubble created by phase change in the ink causes the ink droplet to discharge at a high speed. On the other hand, the ink droplet discharging method utilizing the piezo-electric element is based on
the principle in which the piezo-electric element is displaced by applying the electrical signal to the piezo-electric element and pressure generated by such displacement causes the ink droplet to discharge.
In such an ink jet recording head, there arose a problem that an amount of the ink droplet to be discharged varied from head to head due to variation in manufacture and, thus, printing density varied from ink jet recording head to ink jet recording head.
To solve such a problem, there has been proposed a method in which, during a manufacturing process of the ink jet recording head, ink is actually discharged against a sheet of paper or an exclusive recording medium to from an ink dot, a discharge amount is calculated on the basis of a diameter of the dot, such discharge amount information is stored in a memory mounted to the ink jet recording head, and the discharge amount of the ink jet recording head or an amount of ink applied to the image is changed in accordance with the discharge amount information.
However, in the attempt to suppress the variation in ink discharge amount from head to head in the above-mentioned conventional ink jet recording head, there arose the following problems.
That is to say, in the above-mentioned conventional methods, variation in ink dot diameter occurs due to variation in thickness of an ink receiving layer or in ink permeation/spreading into the receiving layer for each lot of recording media or each recording medium, thereby increasing an error in calculation of the discharge amount.
Further, in the ink jet recording head of the so-called bubble jet type utilizing the electrical/thermal converting elements, since the head itself has a tendency that the discharge amount varies with temperature, in order to measure the discharge amount accurately, the dot diameter must be measured while effecting temperature control with high accuracy, thereby making the recording apparatus and equipment bulky and increasing the cost.
Furthermore, if a size of the liquid droplet itself becomes small, for example, 5 pl, the dot diameter itself is decreased to about 50 xcexcm, then variation in dot diameter measurement exerts a great influence upon the calculation of the discharge amount.
As discussed above, in the technique in which the discharge amount is calculated by effecting the actual discharging/recording, problems arose regarding the accuracy and the cost of the apparatus.
Therefore, an object of the present invention is to provide a method for manufacturing an ink jet recording head, and an ink jet recording head, in which individual differences in discharge amount between respective ink jet recording heads can be measured without actually discharging ink.
To achieve the above object, the present invention provides a method for manufacturing an ink jet recording head comprising a plurality of ink flow paths to which ink is supplied externally, a plurality of energy generating elements provided in the respective ink flow paths and adapted to generate energy utilized for discharging the ink, and a plurality of discharge ports communicated with the respective ink flow paths, and in which the discharge ports are formed by patterning, the method comprising a measuring step for measuring a discharge port area which is an opening area of the discharge port, a step for determining a discharge amount rank which is an index indicating a quantity of the discharge amount (xe2x80x94the discharge amount being subject to variation across different ink jet recording heads due to individual differences between the heads) on the basis of a relationship between the discharge port area and the ink discharge amount, and a step for writing discharge amount information including at least one of the discharge port area, the ink discharge amount having the relationship to the discharge port area, and the discharge amount rank, on a memory mounted to the ink jet recording head.
As mentioned above, in the method for manufacturing the ink jet recording head according to the present invention, since the discharge amount information, including at least one of the discharge port area, the ink discharge amount having the relationship to the discharge port area, and the discharge amount rank as the index for indicating the quantity of the discharge amount (accounting for the individual difference of the recording head) on the basis of the relationship between the discharge port area and the ink discharge amount, is written in the memory mounted to the ink jet recording head, the ink discharge amount of the ink jet recording head (taking into account the individual difference due to variation in manufacture) can be given to the ink jet recording head as the discharge amount information.
Further, the discharge port area may be an opening area of a dummy discharge port which does not contribute to the ink discharging.
In addition, the measuring step may be performed for each manufacturing lot of ink jet recording heads. In this case, since measurement of all of the discharge port areas of the ink jet recording heads is not required, not only can the measuring time be shortened, but also the working can be simplified.
Incidentally, the measuring step may be performed for each ink jet recording head to be manufactured.
The shape of the discharge ports which contribute to ink discharging may be a shape other than a circular shape, and the shape of the dummy discharge port(s) may be a circular shape.
With the arrangement as mentioned above, since the head has a memory in which the discharge amount information, including at least one of the discharge port area, the ink discharge amount having the relationship to the discharge port area, and the discharge amount rank as the index for indicating the quantity of the discharge amount (accounting for the individual difference of the recording head) on the basis of the relationship between the discharge port area and the ink discharge amount, is written, the head can have the ink discharge amount of the ink jet recording head (taking into account the individual difference due to variation in manufacture) as the discharge amount information. Further, when the shape of the dummy discharge port is circular, not only can the measurement of the discharge port area be facilitated, but also the shape of the discharge port from which the ink is actually to be discharged can be designed to be a shape suitable for discharging the ink.
Further, the opening area of the dummy discharge port(s) may be greater than the opening area of the discharge ports which contribute to the ink discharging. The smaller the discharge volume, the smaller the opening area of the discharge ports which contribute to the ink discharging, and, thus, the smaller the discharge port area, and the greater the error due to the measuring resolving power. However, by measuring the dummy discharge port having the greater opening area, the discharge port area can be measured more easily and correctly.
In the ink jet recording head manufactured by the ink jet recording head manufacturing method according to the present invention, since the head has a memory in which the discharge amount information, including at least one of the discharge port area, the ink discharge amount having the relationship to the discharge port area, and the discharge amount rank as the index for indicating the quantity of the discharge amount (accounting for the individual difference of the recording head) on the basis of the relationship between the discharge port area and the ink discharge amount, is written, the head can have the ink discharge amount of the ink jet recording head (taking into account the individual difference due to variation in manufacture) as the discharge amount information.
An ink jet recording method according to the present invention is performed by the ink jet recording head according to the present invention and is characterized in that ink is discharged by communicating a bubble with the atmosphere.
In the ink jet recording method according to the present invention having the above-mentioned feature, since the discharge amount information, including at least one of the discharge port area, the ink discharge amount having the relationship to the discharge port area, and the discharge amount rank as the index for indicating the quantity of the discharge amount (accounting for the individual difference of the recording head) on the basis of the relationship between the discharge port area and the ink discharge amount, is written in the memory mounted to the ink jet recording head, by sending a discharge signal corresponding to the individual difference, variation in recording density due to the individual differences in the discharge amount can be reduced. Further, by discharging the ink by communicating the bubble with the atmosphere, all the ink disposed between the energy generating element and the discharge port can be discharged positively, thereby stabilizing the ink discharge amount.